Caption: Night-blooming cactus. Image 2 of 5. Close-up of the flower of a cactus (Cereus sp.) in bloom after nightfall. This cactus is indigenous to South America. The flowers have a sweet and pervasive fragrance which attracts the hawk moths which pollinate them. The flowers bloom for one night only. The male parts of the flower (the stamens) can be seen, consisting of anthers bearing pollen (yellow) on long filaments extending from the flower's centre. It is a large and hardy cactus, and a popular ornamental plant. (See B620/050-054 for flower opening and closing).